A recent report by the International Agency for Research on Cancer says the dangers of tobacco smoke are greater than had been thought.

The International Agency for Research on Cancer is part of the World Health Organization. It is based in Lyon, France. The agency researches the causes of cancer. It identifies the number of people who develop cancer around the world. And it develops programs aimed at finding ways to prevent the disease. The new report is part of a series written by independent international experts on the dangers of different chemicals.

A committee of twenty-nine experts from twelve countries developed the report. These scientists examined more than fifty medical studies concerning tobacco smoking. The group says that tobacco use is the largest cause of preventable cancers around the world. Experts say that more than one-thousand-million people around the world smoke tobacco.

The report says that one-half of all people who smoke cigarettes will die from diseases caused by smoking tobacco. These include cancers of the lung, stomach, liver, kidney and blood. The report also says tobacco use causes an even greater number of deaths from lung diseases, heart disease and stroke.

The report says other kinds of tobacco use also increase the chances of developing cancers of the lung, head and neck. These include smoking cigars, pipes and bidis -- tobacco rolled in a leaf that is popular in South Asia.

The report also says that people who smoke endanger the health of non-smokers who breathe in tobacco smoke. These non-smokers are breathing in a smaller amount of cancer-causing chemicals than active smokers get. But it is still enough to cause deadly lung cancer.

However, the scientists found no increased risk of cancer among children who breathe in this second-hand smoke. But they say they do not know the long-term effect of tobacco smoke on children as they grow older. The scientists also say their research found that smoking tobacco does not cause some kinds of cancer. There is clear evidence that smoking has little or no effect on developing breast cancer or prostate cancer.

This VOA Special English Health Report was written by Nancy Steinbach.